Such a control or shutoff valve is known from U.S. Pat. No. 2,679,856 A. It has a housing, a valve seat arranged within the housing and a closure element arranged within the housing to be adjustable relative to the valve seat to form a throttling site. A feed channel leading to the valve seat to supply a pressure medium is also provided in the housing. The feed channel formed by a longitudinal groove and a radial channel in an inner housing part leads to a single opening that discharges downstream of the valve seat.
A valve with a valve seat arranged in a housing and a closure element arranged within the housing to be adjustable relative to the valve seat is disclosed in published patent application GB 520 647 A. The valve is formed here by two annular components, between which an annular space is delimited. Water can be introduced into the annular space via a feed line in the housing and via an annular channel and radial holes. However, this annular space discharges downstream of the valve seat for the closure element situated in a closed position.
The valve seat in a steam converting valve disclosed in published application DE 1 269 136 A has steam removal openings positioned concentric to a valve closure element, which is connected via auxiliary steam lines to injection nozzles positioned on the valve outflow side.
DE 1 020 642 A discloses a pressure-reducing control valve in which several channels distributed around the periphery are provided for injection of cooling water at a constriction site of a housing.
A ring nozzle is arranged behind the throttling site in a pressure-reducing valve known from DE 919 570 B.
A valve with a double-walled outflow channel is disclosed in DE 73 25 078 U. The main stream here is enclosed by an oppositely running secondary stream via the annular cavity formed thereby.
A valve in which fine, oblique atomization channels are arranged in the valve seat to form an atomizer is known from DE 712 163.
In the control valves used in the bottom outlets of dams, air is drawn into the pipeline arranged downstream to reduce cavitation. This is made possible by mounting ventilation parts at the outlet of the control valve. Air, which increases the pressure in the throttling gap and reduces the tendency toward cavitation, is drawn in via the partial vacuum on the throttling gap. However, this is only applicable in short pipelines downstream. As soon as the backpressure rises too strongly on the valve, air is no longer drawn in and cavitation is therefore no longer suppressed.
The drawing in of air is not applicable in closed pipeline systems with low backpressure, since the air here leads to undesired pressure fluctuations. In order to reduce cavitation in closed pipeline systems, various control inserts are incorporated in the control valves, which reduce the pressure, reduce the flow rate within the control valve and thereby minimize the development of cavitation. However, the pressure differential often cannot be reduced completely free of cavitation by means of the control insert.